1. Field of the Invention
The present invention relates to a cam-locking dissimilar material sleeve, and more particularly to a cam-locking dissimilar material sleeve which can maximize frictional force without generating plastic deformation.
2. Description of the Related Art
In general, a nuclear power plant mainly includes a nuclear steam supply system around a nuclear reactor, a power generation system such as a turbine for receiving steam and rotating a power generator, and other auxiliary facilities. The nuclear steam supply system is also referred to as a primary system, and the power generation system is also referred to as a secondary system.
Here, the nuclear reactor is an apparatus adapted to artificially control a fission chain reaction of fissile materials to generate heat or for various purposes such as production of radioactive isotopes and plutonium or formation of radiation fields, and is a core element of the primary system.
In the nuclear power generation, electric energy is obtained from steam generated by the nuclear steam supply system including a pressurizer, a steam generator, a main coolant pump, and a reactor where a nuclear fuel is provided, by the power generation system including a turbine and a power generator.
Here, the steam generator is adapted to convert liquid state water of low temperature into steam of high temperature and high pressure by using the heat generated during a nuclear fission, and the steam converted in the steam generator rotates the turbine and the power generator to generate power.
The steam generator includes a heat transfer tube including a plurality of pipes, in which case sludge may be accumulated in the heat transfer tube or the heat transfer tube may be deformed according to how many years the nuclear reactor has been operated. Further, damage such as a small crack may be generated in the heat transfer tube, and the life span of the steam generator may be shortened.
Thus, the steam generator manufacturer recommends the operator to periodically inspect the interior of the steam generator during a preventive maintenance period every year. Accordingly, the heat transfer tube is automatically inspected while an inspection robot installed within the steam generator is moved between heat transfer tubes.
For an inspection of the heat transfer tube, a sleeve is fitted with an expansion shaft installed in the inspection robot, and the expansion shaft with which the sleeve is fitted is inserted into the heat transfer tube. If the expansion shaft is inserted into the heat transfer tube, the sleeve is expanded while the expansion shaft is pulled down.
However, the sleeve according to the related art is mostly manufactured of a metal material, and thus, when expanded by the expansion shaft, the sleeve applies a stress to a surface of the heat transfer tube in contact with the sleeve, disadvantageously causing a flaw.